A method for removing carbon dioxide from the air used in an AFC is known (U.S. Pat. No. 5,595,949, class B 01 J 20/34, 21 Jan. 1997). The method comprises passing air through replaceable containers provided with granules of a porous material, which are impregnated with an alkaline solution. After utilization, the containers with spent material are removed from the device and subjected to regeneration. Regeneration is carried out by decomposing thermally the granules at temperatures of 900-1400° C., at which the carbonates are removed. After decomposing the granules are subjected to hydrolyzation to form alkalis.
A second method of regenerating the spent granules, which is patented in this patent, is the interaction of the formed alkaline metal carbonates with lime or barium hydroxide. Wherewith, insoluble calcium or barium carbonates, which are filtered off, and an alkali, which again impregnates the granules, are formed.
A drawback of the known method is the higher power consumption and labor expenditure of the process of regeneration of the sorbent for absorption of carbon dioxide. Such a method also requires an expenditure of materials, wherein the process of regeneration itself requires special measures from the point of view of safety.
This drawback is partially removed when zeolites are used as the regenerated adsorbents of carbon dioxide (U.S. Pat. No. 6,273,939, class B 01 D 53/04, 14 Aug. 2001). Zeolites purify ambient air of carbon dioxide to a sufficiently deep degree—to 1-2 ppm. The process of adsorption is carried out at a pressure of 1-100 atm., regeneration of the zeolite layer is carried out by blowing with purified air and reducing the pressure to 0.1-5 atm. Wherewith, for complete regeneration, it is necessary to increase the temperature to 50-250° C. The applicant is of the opinion that 250° C. is the most preferable temperature. Wherewith, atmospheric moisture significantly reduces the adsorptive capability of the zeolites in respect to carbon dioxide. In order to restore the sorptive capability of zeolites it is necessary to heat them up to 500-600° C. Thus, use is made of the PSA (TSA, PTSA) method, in which the gas being purified is compressed to certain pressures (from 2 to 100 atm.), at which adsorption of carbon dioxide takes place. Then the pressure is reduced, the purified gas is sent to for utilization, a portion of the purified air—the product gas—is used to clean the adsorbent layer of absorbed impurities.
Use of the PSA method requires substantial consumption of energy, special compressors and a relatively complex method of control.
Drawbacks of these are devices are partially removed in the device known from EP 1 155 729, class B 01 D 53/047, 21 Nov. 2001. The device comprises an air flow blower (a compressor or ventilator), connected by means of pipelines and a stop valve to adsorbers, provided with an adsorbent and connected to an inlet of a utilizer of purified air. The absorber, comprising a layer of activated carbon and a layer of zeolite, is loaded into the adsorbers.
Drawbacks of such a device are the high consumption of energy, complexity of the construction and control of its operation, and also the high consumption of discharged air (several times greater than the quantity of the purified air).
In respect to the combination of essential features and the achieved technical result, the prototype for the method is U.S. Pat. No. 5,595,949, the prototype for the device is EP 1155729.